Capacitive touch switch with false trigger protection

ABSTRACT

An electronics module proximate an exterior surface of a vehicle is disclosed. The module comprises a housing configured for mounting to an interior surface of the vehicle. An electronic circuit is enclosed in the housing. The electronic circuit comprises a proximity sensor and a sensor guard. The proximity sensor is configured to detect an object proximate the housing. The sensor guard is disposed between the interior surface and the proximity sensor and configured to limit a detection by the proximity sensor of an input originating from the exterior surface of a vehicle.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority of U.S. Provisional Application No.62/043,568, filed Aug. 29, 2014, and the entirety of which isincorporated by reference herein.

BACKGROUND OF THE DISCLOSURE

The present disclosure generally relates to a proximity sensor for avehicle, and more specifically relates to an electronics module for avehicle including proximity sensor.

SUMMARY OF THE PRESENT DISCLOSURE

According to one aspect of the present disclosure, an electronics moduleproximate an exterior surface of a vehicle is disclosed. The modulecomprises a housing configured for mounting to an interior surface ofthe vehicle. An electronic circuit is enclosed in the housing. Theelectronic circuit comprises a proximity sensor and a sensor guard. Theproximity sensor is configured to detect an object proximate thehousing. The sensor guard is disposed between the interior surface andthe proximity sensor and configured to limit a detection by theproximity sensor of an input originating from the exterior surface of avehicle.

According to another aspect of the present disclosure, an electroniccircuit for mounting to an inside surface of a windshield of a vehicleis disclosed. The electronic circuit is configured to control a vehicleaccessory and comprises a capacitive sensor, a sensor guard, and aprocessor. The capacitive sensor is configured to detect an object inproximity thereto. The sensor guard is disposed between the windshieldand the capacitive sensor, and the processor is in communication withthe capacitive sensor. The sensor guard is configured to limit a falsedetection by the processor due to an input originating from an outsidesurface of the windshield.

According to yet another aspect of the present disclosure, a trainabletransmitter module for a vehicle is disclosed. The housing is configuredto enclose an electronic circuit and is configured for mounting to aninside surface of a windshield of the vehicle. The electronic circuitcomprises a user interface including a capacitive touch switch having atouch electrode for sensing a proximity of a user's finger or hand. Aguard electrode is positioned between the windshield and at least aportion of the touch electrode. The guard electrode is configured toreduce a possibility that the touch electrode is falsely triggered by aninput originating from an outside surface of the windshield.

The electronic circuit further comprises a backlight for illuminatingindicia on the user interface. A processor is coupled to the touchelectrode, the guard electrode, and the backlight. The processor isconfigured to detect a voltage change on the touch electrode caused bythe user's finger or hand to activate the backlight. The processor mayactivate the backlight in response to the voltage change on the touchelectrode. A trainable transmitter circuitry is coupled to the processorand the processor is configured to control the trainable transmittercircuitry in response to user activation through the user interface.

These and other aspects, objects, and features of the present disclosurewill be understood and appreciated by those skilled in the art uponstudying the following specification, claims, and appended drawings. Itwill also be understood that features of each embodiment disclosedherein may be used in conjunction with, or as a replacement for,features of the other embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a perspective view of an electronics module according to oneembodiment as installed on a windshield of a vehicle;

FIG. 2 is a perspective view of an electronics module according toanother embodiment;

FIG. 3A is an electrical diagram in block form of an electronic circuitincluding a proximity sensor circuit according to one implementation;

FIG. 3B is an electrical diagram in block form of an electronic circuitincluding a proximity sensor circuit according to an alternateimplementation;

FIG. 4 is a block diagram from the perspective of a cross sectional viewof an electronics module installed on a windshield; and

FIG. 5 is a top plan view of a printed circuit board on which theelectronic circuit of FIG. 3A or 3B is disposed.

DETAILED DESCRIPTION OF THE EMBODIMENTS

For purposes of description herein, the terms “upper,” “lower,” “right,”“left,” “rear,” “front,” “vertical,” “horizontal,” and derivativesthereof shall relate to the disclosure as oriented in FIG. 1. However,it is to be understood that the disclosure may assume variousalternative orientations, except where expressly specified to thecontrary. It is also to be understood that the specific devices andprocesses illustrated in the attached drawings and described in thefollowing specification are simply exemplary embodiments of theinventive concepts defined in the appended claims. Hence, specificdimensions and other physical characteristics relating to theembodiments disclosed herein are not to be considered as limiting,unless the claims expressly state otherwise.

Electronics modules of vehicles sometimes include one or more proximitysensors as user actuated buttons in a user interface. One electronicsmodule that may include such proximity sensors is a trainabletransmitter, such as the HOMELINK® trainable transmitter available fromGentex Corporation of Zeeland, Mich. Such trainable transmitters havebeen previously available as factory-installed, in-vehicle components.Such trainable transmitters are integrated into a vehicle, such as bybeing generally permanently mounted on the headliner, a windshieldvisor, a rearview mirror, or the like. Further, the trainabletransmitters can communicate directly with a garage door opener and canbe in the form of a trainable remote garage door opener that can learnthe signal protocols of a remote transmitter that comes with such agarage door opener and later transmit a signal having those protocols.As such, they can accommodate many different garage door openerprotocols using multiple codes and signaling frequencies to provideintegrated vehicle door access. In addition, the HOMELINK® trainabletransmitters are capable of remotely controlling various electricalappliances, such as lights, gates, and security systems.

An electronics module is herein described that may be mounted to theinside of the vehicle windshield such that a proximity sensor includedin the electronics module is located in close proximity to thewindshield. The inventor has recognized a problem with such aninstallation insofar as the proximity sensor may be inadvertentlytriggered in response to an input originating from an outside surface ofthe windshield. For example, the proximity sensor may correspond to acapacitive touch switch having a capacitive touch electrode. Thecapacitive touch electrode may be falsely triggered by an inputoriginating outside the windshield.

The object may correspond to any object, body, or matter proximate anexterior surface of the windshield particularly in a region proximatethe proximity sensor. The object may correspond to various objects orsubstances that may be in proximity with or contact the windshield. Forexample, contaminants (e.g. biological material), rain, or snow on theoutside of the windshield may cause the proximity sensor to falselytrigger a proximity detection. Additionally, the windshield wipers whenpassing in proximity of the proximity sensor may trigger the proximitydetection. The false detection may be particularly problematic whenusing a proximity sensor comprising a capacitive touch switch. This maybe due to a high level of sensitivity of some capacitive touch switchesto various detections that may not correspond to the detection of auser's hand or finger.

Referring to FIG. 1, reference numeral 10 generally designates anelectronics module for installation into a vehicle 12. The module 10 maybe a trainable transmitter module, such as a HOMELINK® trainabletransmitter, and includes a housing 14 disposable against a windshield16 of the vehicle 12 along an interior surface 18 thereof. The housing14 encloses electronic circuitry 30 such as that shown in FIGS. 3A and3B. A user interface 22 is provided that includes one or more buttons26A, 26B, 26C that are exposed at a side of the housing 14 and arecoupled to the electronic circuitry. A backlit indicia 24 may also beprovided in the user interface 22. The module 10 further may include amounting element 20 that may be glued or otherwise secured to thewindshield 16 for coupling the housing 14 to the windshield 16.Alternatively, the housing 14 may be configured to be directly securedto the windshield 16.

FIG. 2 shows an additional embodiment for a windshield-mountedelectronics module 10′. The configuration shown in FIG. 2 has featuressimilar to those discussed in reference to FIG. 1. As such,corresponding features are like numbered for clarity. Though specificembodiments are shown in FIGS. 1 and 2, an electronics module maycorrespond to various combinations and/or variations of the disclosedembodiments without departing from the spirit of the disclosure.

Referring now to FIGS. 3A and 3B, electronic circuitry 30 of theelectronics module 10 may include a user interface 22 including aproximity sensor. As previously discussed, the capacitive sensor maycorrespond to a capacitive touch switch having a touch electrode 34 forsensing proximity of a user's finger or hand. The electronic circuitry30 may further comprise a sensor guard configured to limit the proximitysensor from detect inputs from outside the windshield. The sensor guardmay correspond to a guard electrode 36 positioned between the windshield16 and at least a portion of the touch electrode 34 as shown in FIG. 4.The guard electrode 36 is configured to reduce a possibility that touchelectrode 34 is falsely triggered by noise at an outside surface of thewindshield 16, such as that caused by rain or the vehicle's windshieldwipers.

Though discussed in reference to the capacitive sensor, the proximitysensor may correspond to various forms of sensors that may be utilizedto detect the proximity of an object. For example, the proximity sensormay correspond to a resistive, inductive, capacitive or a variety ofsensors or combinations thereof that may be utilized to detect an objectproximate the housing 14. Each of the sensors may be utilized toaccomplish different sensory functions and may be incorporated in thehousing to provide various functions. In an exemplary embodiment, theproximity sensor is configured to detect the object in the form of ahand or arm of a passenger of the vehicle proximate the user interface22 of the housing 14.

The user interface 22 may further include a backlight 38 forilluminating an indicia 24 (FIGS. 1 and 2). Such indicia 24 may be anindicator light, an icon, or a plurality of indicator lights or iconsthat may correspond to certain functions or buttons, such as buttons26A, 26B, 26C. Buttons 26A, 26B, 26C may correspond to any form ofelectrical of electro-mechanical switches or buttons. For example, thebuttons 26A, 26B, 26C may correspond to mechanical push buttons,capacitive touch switches, or any other form of switches. The capacitivetouch switches may be formed using touch electrodes 34 and guardelectrodes 36 as discussed herein. Thus, multiple touch electrodes 34may be provided. For example, one touch electrode 34 may be provided todetect a proximity of a user's hand such that indicia 24 may beilluminated in response to the detection of the user's hand inproximity. This functionality may improve the visibility of the buttons26A, 26B, 26C such that an operator may selectively activate a specificbutton of the buttons 26A, 26B, 26C one of the buttons via pressing orlightly touching the button.

Electronic circuit 30 may further include a processor 32 communicativelycoupled to the touch electrode 34, the guard electrode 36, and thebacklight 38. The processor 32 may be configured to detect a voltagechange on the touch electrode 34 in response to a detection of aproximity of a finger or hand. In response to the detection of thevoltage change from the touch electrode 34, the processor 32 mayactivate the backlight 38.

The guard electrode 36 may be implemented in a relatively simple form asa ground plane beneath the touch electrode 34. While this implementationmay be effective in reducing signals on the outside of the windshield 16it may also add capacitance between the ground plane and the touchelectrode 34. This may reduce the sensitivity of the touch electrode 34in the desired direction. While this may be acceptable in somesituations, in other cases the sensitivity loss may be too great. Byperforating the ground plane a compromise between sensitivity in thedesired and undesired directions may be affected. Increasing the surfacearea of the perforations or the effective cutout in the ground plane mayreduce the shielding effect in the undesired direction but will alsoincrease sensitivity in the desired direction.

In some embodiments, the guard electrode may correspond to an activelydriven guard electrode 36 as shown in FIGS. 3A and 3B. The guard drivevoltage should match the amplitude and phase of the voltage on the touchelectrode 34; this may be accomplished by generating a signal thatduplicates the signal on the touch electrode 34 (FIG. 3A) or by activelybuffering the touch electrode signal to drive the guard electrode 36with a unity gain amplifier 42 (FIG. 3B). In this way, the effect of thecapacitance between the touch electrode 34 and guard electrode 36 isminimized. The processor 32 further may be configured to provide avoltage on the guard electrode 36 so as to match any voltage changes ontouch electrode 34 and the guard electrode 36. By matching the voltagechanges, the processor may distinguish between a proximity of a user'shand and noise coming from the outside of windshield 16. The processor32 may be implemented using part number PIC16LF1829, available fromMicrochip Technology Inc. of Chandler, Ariz., which includes input pinsto receive signals for touch electrodes and output pins output controlsignals to the guard electrode.

Electronic circuit 30 may include a vehicle accessory circuit, forexample trainable transmitter circuitry 40 coupled to processor 32. Theprocessor 32 may be configured to control the trainable transmittercircuitry 40 in response to a user activation of one or more of thebuttons 26A, 26B, 26C through user interface 22. Although the vehicleaccessory circuit is described herein as a trainable transmittercircuit, it will be appreciated that the vehicle accessory circuit maybe any other form of vehicle accessory, such as a navigation accessory,a radar detector, a tollbooth transceiver, etc.

As shown in FIG. 4, with the housing 14 of the module 10 mounted to aninside surface 18 of windshield 16 by a mounting element 20, guardelectrode 36 is positioned between the windshield 16 and at least aportion of the touch electrode 34. In general, the size of the guardelectrode 36 is commensurate with the size of the touch electrode 34 sothat guard electrode 36 extends between windshield 16 and all portionsof touch electrode 34. However, if guard electrode 36 does not extendbetween windshield 16 and all portions of touch electrode 34, but only aportion of touch electrode 34, guard electrode 36 will still at leastreduce the likelihood of a false trigger due to an input or noiseoriginating from outside the windshield 16.

FIG. 5 demonstrates a portion of a printed circuit board 50 on whichelectronic circuitry 30 is provided. As shown, the guard electrode 36may only extend over a portion of the circuit board 50. The portion ofthe circuit board 50 over which the guard electrode extends maycorrespond to the portion of the circuit board where the touch electrode34 is disposed. The touch electrode 34 may be disposed on a top surfaceof circuit board 50 and may be connected to the circuit board 50 by aflat spring (not shown). A ground plane (not shown) may be provided onthe top surface of the printed circuit board 50. The ground plane mayextend across most of the top surface of the circuit board 50, but mayhave a cut-out area corresponding to the touch electrode 34 and/or guardelectrode 36.

The electronics module 10 may receive power from the vehicle's powersystem or may include a battery and, optionally, a solar cell. In thevarious configurations described herein, the disclosure provides for anelectronics module disposed on a windshield of a vehicle. Theelectronics module comprises a proximity sensor that is resistant toinputs or noise corresponding to objects located outside the windshieldand proximate the proximity sensor. In this configuration, the proximitysensor may limit the unwanted detection of objects outside the vehicle.In this way, the disclosure may provide for a touch electrode configuredto prevent false triggers and/or activations related to undesireddetections.

It will be understood by one having ordinary skill in the art thatconstruction of the described disclosure and other components is notlimited to any specific material. Other exemplary embodiments of thedisclosure disclosed herein may be formed from a wide variety ofmaterials, unless described otherwise herein.

For purposes of this disclosure, the term “coupled” (in all of itsforms, couple, coupling, coupled, etc.) generally means the joining oftwo components (electrical or mechanical) directly or indirectly to oneanother. Such joining may be stationary in nature or movable in nature.Such joining may be achieved with the two components (electrical ormechanical) and any additional intermediate members being integrallyformed as a single unitary body with one another or with the twocomponents. Such joining may be permanent in nature or may be removableor releasable in nature unless otherwise stated.

It is also important to note that the construction and arrangement ofthe elements of the disclosure as shown in the exemplary embodiments isillustrative only. Although only a few embodiments of the presentinnovations have been described in detail in this disclosure, thoseskilled in the art who review this disclosure will readily appreciatethat many modifications are possible (e.g., variations in sizes,dimensions, structures, shapes and proportions of the various elements,values of parameters, mounting arrangements, use of materials, colors,orientations, etc.) without materially departing from the novelteachings and advantages of the subject matter recited. For example, thebezel of the module disclosed herein may take on a variety of shapes andcould be flat, curved, bent, etc. Further, elements shown as integrallyformed may be constructed of multiple parts, elements shown as multipleparts may be integrally formed, the operation of the interfaces may bereversed or otherwise varied, the length or width of the structuresand/or members or connector or other elements of the system may bevaried, or the nature or numeral of adjustment positions providedbetween the elements may be varied. It should be noted that the elementsand/or assemblies of the system may be constructed from any of a widevariety of materials that provide sufficient strength or durability, inany of a wide variety of colors, textures, and combinations.Accordingly, all such modifications are intended to be included withinthe scope of the present innovations. Other substitutions,modifications, changes, and omissions may be made in the design,operating conditions, and arrangement of the desired and other exemplaryembodiments without departing from the spirit of the presentinnovations.

It will be understood that any described processes or steps withindescribed processes may be combined with other disclosed processes orsteps to form structures within the scope of the present disclosure. Theexemplary structures and processes disclosed herein are for illustrativepurposes and are not to be construed as limiting.

It is also to be understood that variations and modifications can bemade on the aforementioned structures and methods without departing fromthe concepts of the present disclosure, and further it is to beunderstood that such concepts are intended to be covered by thefollowing claims unless these claims by their language expressly stateotherwise.

What is claimed is:
 1. An electronics module proximate an exterior surface of a vehicle, the module comprising: a housing configured for mounting to an interior surface of the vehicle; and an electronic circuit enclosed in the housing, the electronic circuit comprising: a proximity sensor configured to detect an object proximate the housing; a sensor guard disposed between the interior surface and the proximity sensor, wherein the sensor guard is configured to limit a detection by the proximity sensor of an input originating from the exterior surface of a vehicle.
 2. The electronics module according to claim 1, wherein the proximity sensor corresponds to a capacitive proximity sensor.
 3. The electronics module according to claim 2, wherein the capacitive proximity sensor comprises a touch electrode configured to detect the object.
 4. The electronics module according to claim 1, wherein the object corresponds to a portion of a body of a passenger of the vehicle.
 5. The electronics module according to claim 1, wherein the sensor guard corresponds to a guard electrode.
 6. The electronics module according to claim 5, wherein the guard electrode is configured to reduce a possibility that the touch electrode is falsely triggered by the input.
 7. The electronics module according to claim 1, wherein the guard electrode is configured is actively driven in response to a signal received from the proximity sensor.
 8. The electronics module according to claim 1, further comprising a user interface having at least one indicia configured to illuminate.
 9. The electronics module according to claim 8, wherein the electronics module is configured to illuminate the at least one indicia in response to the detection of the object proximate the housing.
 10. An electronic circuit for mounting to an inside surface of a windshield of a vehicle and configured to control a vehicle accessory, the circuit comprising: a capacitive sensor configured to detect an object in proximity thereto; a sensor guard disposed between the windshield and the capacitive sensor; and a processor in communication with the capacitive sensor, wherein the sensor guard is configured to limit a false detection by the processor due to an input originating from an outside surface of the windshield.
 11. The electronic circuit according to claim 10, wherein the input originating from the outside of the windshield corresponds to at least one of rain, snow, a wiper blade, and a biological material proximate the windshield.
 12. The electronic circuit according to claim 10, wherein the sensor guard corresponds to a ground plane.
 13. The electronic circuit according to claim 12, wherein the ground plane comprises a plurality of perforations configured to control a sensitivity of the capacitive sensor in a desired direction directed toward an interior of the vehicle.
 14. The electronic circuit according to claim 10, wherein the sensor guard corresponds to a guard electrode.
 15. The electronic circuit according to claim 14, wherein the guard electrode corresponds to an actively driven guard electrode in communication with the processor.
 16. The electronic circuit according to claim 15, wherein the capacitive sensor is configured to output a voltage signal to the controller in response to the detection of the object.
 17. The electronic circuit according to claim 16, wherein the processor is configured to drive the actively driven guard electrode in response to the voltage signal.
 18. The electronic circuit according to claim 16, wherein the processor is configured to drive the actively driven guard electrode by outputting a signal that significantly matches the voltage signal.
 19. A trainable transmitter module for a vehicle, comprising: a housing configured for mounting to an inside surface of a windshield of the vehicle; and an electronic circuit enclosed in the housing, the electronic circuit comprising: a user interface including a capacitive touch switch having a touch electrode for sensing proximity of a user's finger or hand, and a guard electrode positioned between the windshield and at least a portion of the touch electrode, the guard electrode is configured to reduce a possibility that the touch electrode is falsely triggered by an input originating from an outside surface of the windshield; a backlight for illuminating indicia on the user interface; a processor coupled to the touch electrode, the guard electrode, and the backlight, the processor is configured to detect a voltage change on the touch electrode caused by proximity of the user's finger or hand and to activate the backlight in response to the voltage change on the touch electrode; trainable transmitter circuitry coupled to the processor; and wherein the processor is configured to control the trainable transmitter circuitry in response to user activation through the user interface.
 20. The trainable transmitter module according to claim 19, wherein the processor is further configured to drive the guard electrode to significantly match the voltage change detected on the touch electrode. 